ABSTRACT
The present study aimed to assess the effects of drinking water fluoride (F) on the activity of thyroid peroxidase (TPO) enzyme involved in thyroid hormone synthesis. 840 fluorotic patients affected with thyroid hypo and
hyper function and 140 euthyroid without fluorosis representing control were randomly selected from high endemic fluoride areas of Bathinda district, Punjab, India. The findings indicate significant (P<0.001) increase in the levels of serum F, urinary F and Urinary iodine (I) in fluorotic patients affected with thyroid disease. Significant (P<0.001) inhibition was recorded in activity of TPO in fluorotic patients with thyroid hypofunction
and the activity was elevated in hyperthyroid fluorotic patients. Pearson’s bivariate correlation revealed strong positive correlation between water F and serum F (r= 0.98, P<0.01). Negative correlation existed between serum F vs TPO (r= -0.93, P<0.003), urinary I vs TPO (r = -0.95, P<0.002) and serum TSH vs TPO (r = -0.8876, P<0.001). The activity of TPO showed positive correlation with T3 (r = 0.963, P<0.01) as well as with T4 (r = 0.965, P<0.001). From the present study it may be concluded that the ingestion of drinking water with high concentration of fluoride leads to stress of the mechanism of biosynthesis of thyroid hormones, as evidenced by depletion in the activity of TPO, which may be produced by the attraction of fluoride with oxidized form of iodide and/or with the iodide site on the TPO molecule. This tends to decrease in concentration of T3, T4 and increase production of TSH in the serum.